1. Field of the Invention
This invention relates generally to dispensing apparatus and, more specifically, to dispensing apparatus for dissolving a chemical in an ambient fluid. Typical applications would include dispensing a disinfectant, a deodorant or a coloring agent into water in a toilet reservoir, a spa or a hot tub.
2. Description of the Prior Art
In the past, various devices have been used to dispense chemicals into a fluid. One approach to dispensing such chemicals is illustrated by the use of chlorine pellets, such as commonly are used for disinfecting swimming pools. The chlorine pellets were simply dropped within the water of the pool and allowed to dissolve. The rate at which the pellet dissolved was substantially controlled by the surface area exposed to the water. The rate of dissolution was quite rapid when the pellet was placed in the water, and diminished in proportion to the remaining surface area of the pellet, which area was continually reduced by the removal of the outer portions of the pellet. Furthermore, the chlorine pellets were quite mechanically fragile, and could be easily crumbled by mechanical impact as would occur when stepped upon.
Another approach to the dispensation of such chemicals is shown by U.S. Pat. No. 3,521,306, issued to E. C. Jacobs on July 21, 1970. The Jacob's patent teaches the use of a water soluble conditioning material contained within tapered cups, and a housing to be mounted in, for example, a flush toilet reservoir, to retain a plurality of the conditioning material filled cups. The cups were "nested" so that the lower cups had a portion of their previously exposed dissolving surface shielded by a superior other one of the cups, with the uppermost cup having a dissolving surface of the soluble material fully exposed to the fluid in the reservoir. While the dissolution rate of the soluble material within the lower cups was somewhat limited by the interference provided by the upper cups, the rate of dissolution of the soluble material within uppermost cup was substantially unlimited. It can be seen that when a new soluble material filled cup was added, a maximal surface upon which dissolution can occur was provided. The rate of dissolution was thus increased, and as the soluble material entered solution, the tapered nature of the cup reduced the active surface available for entry of the chemical solution. In this manner, the rate of dissolution of the chemical was subject to substantial variation.
A further approach to the dispensation of such chemicals is shown by U.S. Pat. No. 3,837,017, issued to R. L. McDuffee on Sept. 24, 1974. The McDuffee patent teaches the use of a container at least partially filled with an impliedly loose, or granular, cleaning compound. The granular cleaning compound has a surface partially exposed to the fluid within the interior of the container and partially shielded by a plurality of inner pieces, such as stones. The implication that the cleaning compound is not a unitary mass, or solid, arises from the particular teaching of McDuffee that the "insert material may comprise stone, marbles, or any other solid . . . ," while nowhere specifying the composition of the cleaning compound. That implication is further reinforced by the failure of the McDuffee patent to anywhere teach a particular structural configuration for the cleaning compound contained within the container. Indeed, typical commercial applications of the device of the McDuffee patent, such as the "120-day Automatic Bowl Cleaner" have, in fact, utilized a granular compound to provide the cleaning action.
A need existed for a dispensing apparatus useful for dispensing chemicals into water, and having a service life substantially greater than the devices of the prior art.